In 1967, he joined the legendary research and development company Bolt Beranek and Newman (now Raytheon BBN Technologies). At BBN, he helped develop the TENEX operating system, including implementations of the ARPANET and TELNET protocols. In 1971, he developed ARPANET’s first application for network email by combining the SNDMSG and CPYNET programs, allowing messages to be sent to users on other computers. He chose the @ sign to separate local from global emails in the mailing address. Person to person network email was born and user@host became the standard for email addresses, as it remains today.

Thank you, Ray Tomlinson, for inventing email and putting the @ sign on the map. #RIP